Re: GDB 13.1 and clang

Simon Marchi via Gdb
2023-03-09T02:16:23Z

On 3/8/23 17:53, John Baldwin wrote:
> On 3/8/23 1:22 PM, Chris Johns wrote:
>> On 9/3/2023 5:22 am, Simon Marchi wrote:
>>> On 3/8/23 15:07, Chris Johns wrote:
>>>> Hi,
>>>>
>>>> I have just tried to build the latest RTEMS tools and we now use gdb 13.1. I am
>>>> seeing a build failure on FreeBSD 13.1 of:
>>>>
>>>> In file included from ../../gdb-13.1/gdb/xml-tdesc.c:23:
>>>> In file included from ../../gdb-13.1/gdb/target.h:42:
>>>> In file included from ../../gdb-13.1/gdb/infrun.h:21:
>>>> In file included from ../../gdb-13.1/gdb/gdbthread.h:26:
>>>> In file included from ../../gdb-13.1/gdb/breakpoint.h:38:
>>>> ../../gdb-13.1/gdb/target/waitstatus.h:113:1: error: use of undeclared
>>>> identifier 'DIAGNOSTIC_ERROR_SWITCH'
>>>> DIAGNOSTIC_ERROR_SWITCH
>>>> ^
>>>>
>>>> I only have clang installed on the FreeBSD machine.
>>>>
>>>> A quick review of include/diagnostics.h seems to show support for
>>>> DIAGNOSTIC_ERROR_SWITCH only in the gcc area?
>>>
>>> Hmm, I see it in the clang section:
>>>
>>> # define DIAGNOSTIC_ERROR_SWITCH \
>>> DIAGNOSTIC_ERROR ("-Wswitch")
>>>
>>
>> It seems I need to do a better review before posting :)
>>
>>> https://sourceware.org/cgit/binutils-gdb/tree/include/diagnostics.h?h=gdb-13.1-release&id=4f3e26ac6ee31f7bc4b04abd8bdb944e7f1fc5d2#n76
>>>
>>> Unless there's a typo I don't see.
>>>
>>> diagnostics.h is included at the top of waitstatus.h. Is it possible
>>> that another unrelated diagnostics.h gets included on FreeBSD? You
>>> could inspect the preprocessed file to see what the preprocessor
>>> included for diagnostics.h.
>>
>> There is another version installed here:
>>
>> $ pkg which /usr/local/include/diagnostics.h
>> /usr/local/include/diagnostics.h was installed by package binutils-2.37_2,1
>>
>> We have /usr/local/include early in the include list on FreeBSD to pick up some
>> of the required libraries installed as packages. I will check for a package
>> update or I revisit the build flags to see how it can be handled.
>>
>> Thank you for the prompt and helpful responses.
>
> Yes, I manually delete all the headers installed by binutils into
> /usr/local/include when building GDB from source locally to work
> around this. :( I'm not sure of the best fix for this. I tracked
> it down to the change to add zstd as ZSTD_CFLAGS is before BFD_CFLAGS
> in INTERNAL_CFLAGS_BASE in Makefile.in in this commit:
>
> commit 2cac01e3ffff74898c54fa5e6418817f5578adb6
> Author: Fangrui Song <maskray@google.com>
> Date: Mon Sep 26 19:50:13 2022 -0700
>
> binutils, gdb: support zstd compressed debug sections
> PR29397 PR29563: Add new configure option --with-zstd which defaults to
> auto. If pkgconfig/libzstd.pc is found, define HAVE_ZSTD and support
> zstd compressed debug sections for most tools.
> * bfd: for addr2line, objdump --dwarf, gdb, etc
> * gas: support --compress-debug-sections=zstd
> * ld: support ELFCOMPRESS_ZSTD input and --compress-debug-sections=zstd
> * objcopy: support ELFCOMPRESS_ZSTD input for
> --decompress-debug-sections and --compress-debug-sections=zstd
> * gdb: support ELFCOMPRESS_ZSTD input. The bfd change references zstd
> symbols, so gdb has to link against -lzstd in this patch.
> If zstd is not supported, ELFCOMPRESS_ZSTD input triggers an error. We
> can avoid HAVE_ZSTD if binutils-gdb imports zstd/ like zlib/, but this
> is too heavyweight, so don't do it for now.
> ```
> % ld/ld-new a.o
> ld/ld-new: a.o: section .debug_abbrev is compressed with zstd, but BFD is not built with zstd support
> ...
> % ld/ld-new a.o --compress-debug-sections=zstd
> ld/ld-new: --compress-debug-sections=zstd: ld is not built with zstd support
> % binutils/objcopy --compress-debug-sections=zstd a.o b.o
> binutils/objcopy: --compress-debug-sections=zstd: binutils is not built with zstd support
> % binutils/objcopy b.o --decompress-debug-sections
> binutils/objcopy: zstd.o: section .debug_abbrev is compressed with zstd, but BFD is not built with zstd support
> ...
> ```
>
> I have not tried moving ZSTD_CFLAGS after BFD_CFLAGS, but if it worked I
> think the right solution is to ensure all the "local" includes for things
> in git come first before any includes that pull from the installed system.
> I think this would mean moving READLINE_CFLAGS (for systems that use a
> system readline), ZLIBINC, and ZSTD_CFLAGS after INCLUDE_CFLAGS.
>
> I just tried this and it worked for me locally:
>
> diff --git a/gdb/Makefile.in b/gdb/Makefile.in
> index 6e39383eb93..40497541880 100644
> --- a/gdb/Makefile.in
> +++ b/gdb/Makefile.in
> @@ -629,8 +629,8 @@ INTERNAL_CPPFLAGS = $(CPPFLAGS) @GUILE_CPPFLAGS@ @PYTHON_CPPFLAGS@ \
> # INTERNAL_CFLAGS is the aggregate of all other *CFLAGS macros.
> INTERNAL_CFLAGS_BASE = \
> $(GLOBAL_CFLAGS) $(PROFILE_CFLAGS) \
> - $(GDB_CFLAGS) $(OPCODES_CFLAGS) $(READLINE_CFLAGS) $(ZLIBINC) \
> - $(ZSTD_CFLAGS) $(BFD_CFLAGS) $(INCLUDE_CFLAGS) $(LIBDECNUMBER_CFLAGS) \
> + $(GDB_CFLAGS) $(OPCODES_CFLAGS) $(BFD_CFLAGS) $(INCLUDE_CFLAGS) \
> + $(READLINE_CFLAGS) $(ZLIBINC) $(ZSTD_CFLAGS) $(LIBDECNUMBER_CFLAGS) \
> $(INTL_CFLAGS) $(INCGNU) $(INCSUPPORT) $(LIBBACKTRACE_INC) \
> $(ENABLE_CFLAGS) $(INTERNAL_CPPFLAGS) $(SRCHIGH_CFLAGS) \
> $(TOP_CFLAGS) $(PTHREAD_CFLAGS) $(DEBUGINFOD_CFLAGS) $(GMPINC) \

If it works, I'd be fine with that patch. We'll need a PR number for
the patch to make it to the 13 branch though.

Simon